Kinetics and mechanism of the oxidation of alkyl and aryl methyl ketones by permanganate ion in aqueous ethanoic acid

The kinetics of electron-transfer reactions between permanganate ion and et hyl and aryl methyl ketones have been studied in aqueous MeCO2H acid medium in the presence of HClO4 at different temperatures. For ethyl methyl keton e and XC6H4COMe (X = p-Cl, p-Br or p-NO2) the reaction obeys the rate law - d[MnO4-]/dt = (kK(e)[H+][MnO4-][RCOMe])/(l + K-e[H+][RCOMe]). But the oxida tions of XC6H4COMe (X = p-Me and p-OMe) follow the rate equation -d[MnO4-]/ dt = k(3)[H+][MnO4-][RCOMe]. The reaction involves a fast pre-equilibrium w ith intermediate formation of a permanganate ester before the two-electron transfer, rate-determining, step. A number of thermodynamic parameters have been evaluated.